As shown in FIG. 5, a bandpass filter 200, for example, usually has an unbalanced input terminal 202 and an unbalanced output terminal 204, providing an unbalanced input/unbalanced output type.
If the bandpass filter 200 is to be connected to a balanced-input high-frequency amplifying circuit 206, for example, then a balun (unbalanced to balanced converter) 208 is connected between the unbalanced output terminal 204 of the bandpass filter 200 and the high-frequency amplifying circuit 206.
As shown in FIG. 6, the balun 208 has an unbalanced line 212 connected to an unbalanced input terminal 210, a first balanced line 216a connected between a first balanced output terminal 214a and ground, and a second balanced line 216b connected between a second balanced output terminal 214b and ground (see, for example, Patent Document 1). The balun 208 is constructed as a distributed-constant circuit having a plurality of striplines, each having an about λ/4 length, provided in a dielectric substrate, for example. The balun 208 is thus small in size, contributing to a size reduction of an electric device that includes the bandpass filter 200 and the balun 208.
Heretofore, there has been proposed a laminated electronic component having a base which comprises a dielectric layer and a magnetic layer that are joined to each other (see, for example, Patent Document 2). The laminated electronic component is solely aimed at preventing the product from suffering warpage, delamination, and cracking by adding a dummy layer thereto. It has been unclear, however, if the laminated electronic component can achieve an object to adapt an FM radio receiver and/or an FM transmitter in a portable device.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2003-7538
Patent Document 2: Japanese Laid-Open Patent Publication No. 2003-37022